1. The Field of the Invention
The present invention relates to a method and apparatus for controlling the proportioned flow of granular, namely non liquid and non gaseous, solid material, which is capable of fluent motion, from a single inlet to between two outlets of like dimensions. In particular, the present invention pertains to a method and apparatus which allows easy control of the proportioning of flowing non gaseous and non liquid materials, which are generally either granular or powder in form, from a single source to between two like outlets while avoiding undue wear of the components.
2. The Prior Art
There has been a need for a reliable means to proportion flowing fluant materials which are neither liquid nor gaseous. Most of the devices theretofore proposed have suffered from the disadvantage of being subject to eroding wear by flowing granular or powder solid material, which have the characteristic of being abrasive. Such material has had the tendency to either jam the flow diverting means making control impossible, or rapidly wearing away control surfaces thereby requiring frequent replacement with the attendent costs of replacement and down time for the repairs. Generally these repairs were difficult to make and expensive.
Another problem of the prior art is the known proportioning devices must be placed in such fashion that the downstream pipelines are carefully balanced in pressure drop in order to obtain an accurate split of the material. As the diverting means was eroded, the flow of the material would become erratic due to the uneven surface created on the deflection means.
One industry which has a need for flow proportioning is the power genenrating industry, specifically for coal fired power generating plants. Coal of a high sulfur content has been used in many areas of the country and has resulted in the undesirable generation of air polutants, specifically sulfuric acid. These problems have been largely overcome by the injection of limestone into the combustor to neutralize the resultant sulfuric acid generated with the exhaust gases. In order to produce an even flow of limestone, it is generally necessary to provide four to eight injection lances for each furnace. Generally the lances have been fed by a single pneumatic conveying system, with flow splitters located periodically to evenly divide the solids among the lances. Such splitters have been provided by several companies, such as the Fuller Company, Dacon Fluid Technology, and Allen-Sherman-Hoff Company.
However, due to the abrasiveness of limestone, having any mechanism located in the flow stream must be avoided if at all possible. Heretofor, most designs incorporated a symmetrical piping configuration on the discharge side to prevent short circuiting of the material in one pipeline or the other.